"Make no mistake, we have had a fairly dedicated police response. It was actually investigated in the first couple of hours (of Michael going missing)," Supt Johnson said.

"All those early inquiries were happening, it just wasn't in the public domain. Officers from the child protection branch were out there the first day seeking information."

Sunshine Coast SES controller Janet Scott said they had about 23 volunteers out, working in four teams, combing through Dularcha National Park at Landsborough.

A number of them had been involved in extensive land searches on Saturday and Sunday, aided up by aerial support.

The search ramped up again on Sunday, after police found what they believed to be Michael's pushbike on Saturday.

Ms Scott said some of the terrain being encountered by search teams was "pretty rough, fairly thick forest".

She said teams were searching near the train line running through the park, and it was "quite steep" with a lot of bracken fern, and quite dense bush in around a number of little creeks.

She said they were searching for any belongings, or Michael himself, and were attempting to conduct a line search wherever the terrain would allow, as they covered "a lot of land" today before darkness brought today's search to an end.